Hygienic Design. What's that about?

I'm working in neutraceuticals at the moment, so hygienic design is a key concept. Even the process water systems are hygienic, though the word means different things in different industries, and different countries.

I like words, so this just adds to the interest for me. As I signed s contract to write s dictionary of terms used in chemical engineering practice last week for Elsevier, it's just as well I like words...